What book is your class going to use? One suggestion would be to start going through the book now. Also, you said you did average in your proof writing class, so my suggestion would be to go through all that stuff again and make sure you understand it well (proof writing practice will definitely help you in your Real Analysis class).
I think the best way to prepare would be just practice doing proofs, post questions here if you have any. More importantly, be prepared to spend as much time as you need to understand everything. Do not fall behind. If you have any questions, post them here, and/or ask your professor at office hours. If you put in the effort (time), you should be able to pass. I went to my professor's office nearly every week when I took the first and second semesters of Real Analysis, and I got an A+ in both. It was not easy, and I spent a great amount of time on both classes (especially the second), but it was worth it.